This invention relates to a centrifugal separator of a type which can be used to extract heavy material such as gold from a slurry containing the metals mixed with other materials.
The issued U.S. Pat. Nos. 4,608,040 and 4,846,781 of the present applicant disclose a device of this type which comprises a centrifuge bowl having a base in a peripheral wall surrounding an axis passing through the base and generally upstanding from the base to an open mouth, a plurality of axially spaced inwardly projecting rings mounted on the inner surface of the peripheral wall and a plurality of openings extending through the peripheral wall from the outer surface to the inner surface thereof, the openings being arranged between each ring and the next adjacent ring and spaced around the peripheral wall, means for mounting the bowl for rotation about the axis, means for feeding the material into the bowl so that during rotation of the bowl the materials flow over the peripheral wall and discarded materials discharge from the open mouth while collected materials remain in the recesses between the rings as a concentrate, the materials between the rings being fluidized to cause a separation effect in the materials to preferentially collect the heavy metals.
This device has been found to operate very satisfactorily and in a considerably improved manner relative to prior devices such as those shown in the older Canadian Patent No. 111809 and in old Australian Patents Nos. 22055/35 and 17487/34 (MACNICOL).
However, all of these devices are batch devices in that the bowl is rotated for a period of time until a pre-determined quantity of material has passed through the bowl after which the separation efficiency can deteriorate due to the fact that the recesses have a large proportion of the heavy metals already separated so that further heavy metal can fail to properly separate and can be discarded. At this time it is necessary to stop the process including halting the bowl and the flow of feed materials and water into the bowl following which the bowl must be cleaned out and the concentrate collected. This shut down of the machine is of course highly undesirable in that it interfers with the otherwise continuous processing of the feed material, in that the clean out requires a relatively high level of manual activity and in that the shut down of the machines increases the number of machines which are required to process a certain quantity of materials.
It has been therefore an objective of many people in this field to provide a machine which will operate continuously without necessity for regular shut down for collection of the concentrate. Up until now, however, no machine of this general type is available for continuous operation despite the obvious requirement for a continuous operating machine of this type.
It is one object of the present invention, therefore, to provide a centrifugal separating machine of the general type described above which can operate continuously without the necessity for periodic shutdown of the machine for the cleaning operation.
According to the first aspect of the invention, therefore, there is provided apparatus for centrifugally separating intermixed materials of different specific gravities comprising a centrifuge bowl having a base and a peripheral wall surrounding an axis passing through the base and generally upstanding from the base to an open mouth, axially spaced inwardly projecting peripherally extending members defined on an inner surface of the peripheral wall so as to provide a peripherally extending recess between each member and the next adjacent member, means for mounting the bowl for rotation about the axis, means for feeding materials into the bowl such that during rotation of the bowl the materials flow over the peripheral wall for discharge of discarded materials from the open mouth and for collection of a concentrate in the recesses, and means for removing the concentrate from each of the recesses comprising duct means, means for mounting the duct means so as to project into the bowl, a probe portion on the duct means for projecting into a respective one of the recesses, mouth means on the probe portion such that the material is the recess is caused to flow into the mouth means and means for moving the duct means from a first position in which the probe portion is inserted into the recess to a second position in which the probe portion is removed from the recess.
According to the second aspect of the invention, there is provided a method of centrifugally separating intermixed materials of different specific gravities comprising providing a centrifuge bowl having a base in a peripheral wall surrounding an axis passing through the base and generally upstanding from the base to an open mouth, the bowl having axially spaced inwardly projecting peripherally extending members defined on an inner surface of the peripheral wall so as to provide a peripherally extending recess between each member and the next adjacent member, rotating the bowl about the axis, feeding materials into the bowl such that during rotation of the bowl the materials flow over the peripheral wall with discarded materials discharging from the open mouth and retained material being collected on the peripheral wall within each of the recesses as a concentrate, temporarily inserting into each recess a probe portion of a duct member so as to cause material within the recess to flow into a mouth of the probe portion, and withdrawing the material from the duct member into a separate storage container.
With the foregoing in view, and other advantages as will become apparent to those skilled in the art to which this invention relates as this specification proceeds, the invention is herein described by reference to the accompanying drawings forming a part hereof, which includes a description of the best mode known to the application and of the preferred typical embodiment of the principles of the present invention, in which: